1. Field of the Invention
This invention relates to expanded polystyrene and particularly to expanded polystyrene rasps having replaceable rasp elements.
2. Description of the Prior Art
Expanded polystyrene (EPS) sheets are commonly used in the field of wall surfacing. These products are usually sold in large sheets (typically 2′×4′), which are affixed to building sheathing. The sheets have seams between them that are usually uneven. In addition, the surfaces are normally covered in a thin plaster coating commonly called “mud”. This EPS foam is typically sanded to produce a smooth finish for base coating. Many products exist for sanding and preparing the EPS foam boards. These are typically sanding blocks that have abrasive grit papers that are attached. Other tools are rasps that have larger abrasive pieces attached that are more aggressive than sandpapers.
The problems that all these devices suffer from are common; sandpaper quickly dulls and wears out, which requires frequent changing of the paper. Standard rasps are likely to get clogged and worn down over time, which again, requires their replacement. Finally, both the sandpaper and rasps can become contaminated with mud that has not fully hardened. In the case of sandpaper, this simply requires replacing the sheet. In the case of rasps, this requires prompt washing of the rasp to remove the mud. Otherwise, if the mud hardens, it is almost impossible to remove it and not damage the rasp's abrasive surface. Once mud has hardened, the rasp becomes almost unusable.
Another problem with sandpapers and rasps is that foam particles build up underneath the rap. This reduces the effectiveness of the tool because it starts to “hydroplane”. This is caused by loose foam balls that cause the rasp to slip or slide across the surface, which reduces the rasp's ability to cut through the foam to smooth it.
Finally, the prior art rasps have grit that is closely clustered together. His close spacing produces a lot of friction that makes it difficult to move the rasp across the EPS foam surface. Thus, these tools require the user to expend more energy to make the tool work.